little explanation of why:
the reflection came after concerns about more or less pronounced oscillations depending on the installations, mainly after the periods of reduced when the circuit is cold and particularly if it has a large inertia (heated floor, many large radiators). I recall the facts:
BE CAREFUL, this is not the same problem as the close stops / departures of the burner. here the burner operates during the whole phase of the oscillations.
small explanatory graph:
when the boiler is on standby, the moment comes when its temperature drops below the lower limit and the burner restarts. Unfortunately, the regulation is made in such a way that it is also this same temperature which is the lower limit for closing the V3V.
-the latter therefore closes to prevent the cold return of the radiators to go even further to cool the boiler.
- during this time, the boiler starts its small fire of pellets and raises its internal temperature.
-when it goes back above the threshold, the V3V reopens.
-the cold water therefore arrives in the boiler, the temperature of which drops below the threshold, hence the closing of the V3V, etc.
as the V3V is slow, the oscillation has a large amplitude in temperature.
the idea is to control the circulator which is much faster to start and to stop, hence better reactivity and suppression of oscillations.
with the regulation, you cannot control the circulator, it turns even during the closing phases of the V3V, hence the use of the boiler's UW port.
after....
